This invention relates generally to apparatus for uniformly distributing conditioned air across the full width of an indoor coil of an air conditioner unit.
In U.S. Pat. No. 4,951,737 there is disclosed a packaged terminal air conditioner (PTAC) unit that has an indoor section and an outdoor section that are separated by a dividing wall. Each section contains a heat exchanger or coil and a fan for moving air over the coil surfaces. The fan utilized in the indoor section is a cross flow blower wheel fan that extends laterally across the width of the indoor coil. The cross flow blower contains a series of elongated curved blades that are spaced apart to form a cylindrical unit. The fan is driven by a motor at one end and draws return air through the indoor coil and circulates the conditioned air leaving the coil back into the comfort region. The outdoor fan servicing the outdoor coil is a centrifugal fan that requires the use of a second motor.
A similar type PTAC unit is disclosed in a later U.S. Pat. No. 4,944,654, in which the cross flow blower used in the indoor section of the unit is replaced with a centrifugal fan that is driven along with the outdoor fan by a single fan motor. The indoor fan, in this case, is equipped with forward curved blades and is mounted within a split scroll arrangement. The scroll increases in diameter to either side of a cut off point which is located at about the horizontal center line of the blower. Each section of the split scroll is a curved wall defining a logarithmic scroll, both scrolls arranged to discharge air into a plenum that extends horizontally to either side of the wheel above the indoor coil. It has been found, however, that a rather large area of reduced flow is created within the plenum that is generally located directly over the blower. A noise reducing baffle is mounted in the area of reduced flow that further impedes flow in this critical region.
It should be further noted that the size and positioning of the scrolls employed in the split scroll arrangement is limited by the available space in this part of the air conditioning unit. This, in turn, limits the amount of air that can be handled by the split scroll system. In addition, the forwarded curved blades of the blower tend to be relatively noisy.
It is therefore an object of the present invention to improve air conditioning units and, in particular, packaged terminal air conditioner (PTAC) units.
It is a further object of the present invention to improve the air handling capabilities of the indoor section of a PTAC unit.
It is a still further object of the present invention to improve the air handling capabilities of the indoor section of an air conditioning unit that employs a centrifugal blower.
Another object of the present invention is to improve the uniformity of air distribution in the indoor section of an air conditioning unit.
Yet a further object of the present invention is to reduce the amount of noise produced by a PTAC type unit.
These and other objects of the present invention are attained by air handling apparatus suitable for use in an air conditioning unit having an indoor section that is separated from an outdoor section by a divider wherein each section has a fan and a heat exchanger coil. A housing is mounted behind the indoor coil that has a blind opening passing inwardly through the front wall of the housing which faces the indoor coil. The opening has a rectangular shaped upper section that extends laterally above the top of the coil and a volute shaped lower section that houses a centrifugal blower wheel having rearwardly curved blades and which opens upwardly through the bottom wall of the upper section. The lower section contains a scroll shaped wall that is generally centered about on the axis of the blower wheel whose radius of curvature increases from a cut off region at about the 2 o""clock blower location through an arc of about 200xc2x0. A second linear wall is positioned tangent with the distal end of the scroll wall and extends upwardly to intersect the bottom wall of the upper section of the opening to establish an exit region through which conditioned air that is drawn into the housing by the blower wheel is uniformly distributed across the upper section of the opening and is discharged back into the comfort region.